1. Field of the Invention
This invention relates to liquid metering devices of the type which are attached to or installed upon liquid product containers to normally maintain the outlets of such containers closed during periods of nonuse, but which, when actuated, are operable to dispense by gravity relatively precise amounts of liquid contents.
2. Description of the Prior Art
Devices for dispensing premeasured amounts of liquid from a container have been used for many years. For example, the device disclosed in U.S. Pat. No. 3,091,374 dispenses teaspoon-sized doses of medicine from a bottle. In use, this device is coupled to a threaded medicine bottle by a snugfitting tubular insert received within the bottle neck and an outer tubular rotatable cap threadably coupled to the outside of the bottle neck. In operation, the bottle is inverted which causes a measuring chamber defined by the device structure to fill, the device outlet being closed by the action of a compressed spring holding the valve stem against an outlet hole in the center of the movable cap. Holding the bottle inverted with one hand, the user's other hand rotates and thereby extends the cap axially beyond the travel limit of the stem. This action opens the outlet hole, closes the chamber inlet, and dispenses the medicine through the outlet hole. The cap is then counter-rotated to reinitiate the dispensing cycle.
The foregoing device and other similar existing devices present a number of significant problems. For example, in using the device described above both hands are normally required, one to hold the bottle upside down and the other to rotate the cap. This device also requires the use of a helical spring which is subject to failure, may contaminate the product, and adds significantly to the expense of the device. The outlet hole, because of its size and position, is subject to clogging and requires that the bottle be held nearly perfectly vertically in order for the measured amount of liquid to totally dispense. Additionally, the cap may be inadvertently removed from the bottle neck during rotation. Finally, the device has no shipping mode whereby the container with the liquid can be shipped with the device in place and with both the inlet and outlet closed. The known prior art devices have all or many of these problems inherent in their structure.